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7029167: add support for conditional card marks

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Reviewed-by: iveresov, kvn
This commit is contained in:
Tom Rodriguez 2011-04-27 15:40:36 -07:00
parent 6c8fc4b347
commit 2126589fd0
3 changed files with 32 additions and 5 deletions
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21
hotspot/src/share/vm/opto/graphKit.cpp
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@ -3447,9 +3447,22 @@ void GraphKit::write_barrier_post(Node* oop_store,
// Get the alias_index for raw card-mark memory
int adr_type = Compile::AliasIdxRaw;
// Smash zero into card
Node* zero = __ ConI(0);
Node* zero = __ ConI(0); // Dirty card value
BasicType bt = T_BYTE;
if (UseCondCardMark) {
// The classic GC reference write barrier is typically implemented
// as a store into the global card mark table. Unfortunately
// unconditional stores can result in false sharing and excessive
// coherence traffic as well as false transactional aborts.
// UseCondCardMark enables MP "polite" conditional card mark
// stores. In theory we could relax the load from ctrl() to
// no_ctrl, but that doesn't buy much latitude.
Node* card_val = __ load( __ ctrl(), card_adr, TypeInt::BYTE, bt, adr_type);
__ if_then(card_val, BoolTest::ne, zero);
}
// Smash zero into card
if( !UseConcMarkSweepGC ) {
__ store(__ ctrl(), card_adr, zero, bt, adr_type);
} else {
@ -3457,6 +3470,10 @@ void GraphKit::write_barrier_post(Node* oop_store,
__ storeCM(__ ctrl(), card_adr, zero, oop_store, adr_idx, bt, adr_type);
}
if (UseCondCardMark) {
__ end_if();
}
// Final sync IdealKit and GraphKit.
final_sync(ideal);
}

13
hotspot/src/share/vm/opto/macro.cpp
View File

@ -221,9 +221,16 @@ void PhaseMacroExpand::eliminate_card_mark(Node* p2x) {
Node *shift = p2x->unique_out();
Node *addp = shift->unique_out();
for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) {
Node *st = addp->last_out(j);
assert(st->is_Store(), "store required");
_igvn.replace_node(st, st->in(MemNode::Memory));
Node *mem = addp->last_out(j);
if (UseCondCardMark && mem->is_Load()) {
assert(mem->Opcode() == Op_LoadB, "unexpected code shape");
// The load is checking if the card has been written so
// replace it with zero to fold the test.
_igvn.replace_node(mem, intcon(0));
continue;
}
assert(mem->is_Store(), "store required");
_igvn.replace_node(mem, mem->in(MemNode::Memory));
}
} else {
// G1 pre/post barriers

3
hotspot/src/share/vm/runtime/globals.hpp
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@ -620,6 +620,9 @@ class CommandLineFlags {
product(bool, UseSSE42Intrinsics, false, \
"SSE4.2 versions of intrinsics") \
\
product(bool, UseCondCardMark, false, \
"Check for already marked card before updating card table") \
\
develop(bool, TraceCallFixup, false, \
"traces all call fixups") \
\